// 常量和变量的定义及使用
main() {
  // 定义变量
  var num1 = 100; //100
  var name = "老王"; //"老王"

  // 打印常量和变量
  print("num1 = $num1"); //num1 = 100
  print("name = $name"); //name = "老王"

  // 修改变量的值
  print(++num1); //101
  print(name = "老李"); //"老李"

  // 常量的定义
  const PI = 3.1415926; //3.1415926
  print("PI = $PI"); //PI = 3.1415926

  final num2 = 200+PI; //200+3.1415926
  print("num2 = $num2"); //num2 = 203.1415926

} 

